Make Windows Bootable Again If You Deleted System Partition by Mistake

Here, we mainly introduce 3 ways to restore system: use free third party program, employ diskpart of Windows installation disc, and reinstall Windows

Trick: please try the first method, then the second one, and the last one. Try the latter one only when the former one failed to work.

Method 1: Fast Recover System Partition with MiniTool Partition Wizard Bootable Edition

This is the simplest method, and it perfectly worked on our testing machine.

MiniTool Partition Wizard Bootable Edition can help Windows users complete various partitioning operations when Windows is unbootable, including recover lost/deleted partition, rebuild MBR, resize system partition/boot partition, clone disk/partition, and so on.

To use this bootable partition manager to recover partition, you should purchase a paid version. If you are not a Server user, the Professional Edition is available.

Warning: please check all useful partitions, both existing and lost/deleted, because unchecked partitions will be lost.

Note: remember to set the hard disk where Windows is installed to the first boot device if you are employing Legacy BIOS.

Method 2: Fix Boot Information with Windows Installation Disc

Tip: we have tested the following methods on virtual machine, which are finally proved to be useful. So, it is worth trying them, but we can't 100% guarantee that they work for you.

To use this method, please prepare a Windows installation disc which had better be the one you used to install Windows. Of course, the one holding the same version as your Windows is also available.

Then, you can start fixing.

However, since there are 2 types of system partitions, namely system reserved partition and EFI system partition, we will show operations separately.

For Legacy BIOS Users

Tip: this method will not create a new system reserved partition but do fix only. So, if you want such a partition, try other methods.

Firstly, please boot computer from the installation media to get the interface below:

recover system reserved partition in diskpart windows setup interface

Then, press on Shift + F10 combination keys to call out Command Prompt, and type following characters.

Trick: every type in Command Prompt as well as Diskpart should end with pressing on Enter key.

In the window of Command Prompt, type diskpart to activate this partitioning tool. Then, type the following commands to set Windows OS partition (C drive most of the time) active:

List disk

Select disk #
(# is the number of the disk where your Windows is installed)

List partition

Select partition #
(here # is the number of the Windows OS partition rather than system reserved partition)

Active

After setting the partition active, please type exit to quit from diskpart.

Then, in Command Prompt please type the following commands to fix boot information:

Bootrec /fixmbr

Bootrec /fixboot

Bootrec /rebuildBCD

The bootrec /rebuilBCD command will search for Windows installations not included in the Boot Configuration Data (BCD) and then ask you if you'd like to add one or more to it. Just type Yes and then Exit to quit from Command Prompt.

Then, you can take out the installation media, and your Windows is very likely to be bootable again.

For UEFI Users

Before fixing boot, please launch MiniTool Partition Wizard Bootable Edition to view partition layout at first. In the section Fast Recover System Partition with Partition Wizard Bootable Edition we have introduced how to create a bootable partition manager, so here we skip this step.

Once the bootable partition manager is created, boot your computer via the disc. Then, MiniTool Partition Wizard will show you disk and partition layout.

If there is no unallocated space for EFI system partition on the left side of C drive, you can shrink your C drive via the Move/Resize Partition function to create one, which could be the size of your original EFI partition or larger. If there is such an unallocated space, skip this step, and just select the very unallocated space, create a FAT32 partition here, and label the partition with efi system.

Tip: we can't format the EFI partition to NTFS, because UEFI firmware does not recognize NTFS.

At last, click "Apply" button to make all changes executed.

After that, you can quit from Partition Wizard bootable disc and start your computer via Windows installation media. Then, press on Shift + F10 combination keys to activate Command Prompt and type the following command:

bcdboot C:\windows

Bcdboot copies boot files from the Windows partition to the EFI system partition and creates the BCD store in the same partition.

Tip: if Windows isn't installed in C drive, please replace C with the letter of your exact Windows OS partition.

Then, you can remove Windows installation disc and restart your computer.

Nevertheless, if both recovering system served partition and fixing boot information fail to make your Windows bootable again, you'll need to reinstall Windows.